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The origin of Cosmic Rays: New developments and old puzzles K. Blum*, B. Katz*, A. Spector, E. Waxman Weizmann Institute *currently at IAS, Princeton
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The cosmic ray spectrum [From Helder et al., SSR 12]
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Cosmic-ray E [GeV] log [dJ/dE] 1 10 6 10 E -2.7 E -3 Heavy Nuclei Protons Light Nuclei? Galactic UHE X-Galactic [Blandford & Eichler, Phys. Rep. 87; Axford, ApJS 94; Nagano & Watson, Rev. Mod. Phys. 00; Lemoine, J. Phys. 13] Source: Supernovae(?) Source? Lighter
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The cosmic ray generation spectrum
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UHE (>10 9.5 GeV=10 1.5 EeV)
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UHE: Composition HiRes 2005 Auger 2010 HiRes 2010 (& TA 2011) [Wilk & Wlodarczyk 10]* [*Possible acceptable solution?, Auger collaboration 13]
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UHE: Anisotropy & Composition Galaxy density integrated to 75Mpc CR intensity map ( source ~ gal ) [EW, Fisher & Piran 97] Biased ( source ~ gal for gal > gal ) [Kashti & EW 08] Anisotropy @ 98% CL; Consistent with LSS Anisotropy of Z at 10 19.7 eV implies Stronger aniso. signal (due to p) at (10 19.7 /Z) eV [ since: Acceleration of Z(>>1) to E ~ Acceleration of p to E/Z, p(E/Z) propagation = Z(E) propagation, n p >= n Z at the source.] Not observed No high Z at 10 19.7 eV [Kotera & Lemoine 08; Abraham et al. 08… Foteini et al. 11] [Lemoine & EW 09]
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[EW 1995; Bahcall & EW 03] [Katz & EW 09] 2 (dN/d ) Observed = 2 (dQ/d ) t eff. (t eff. : p + CMB N + Assume: p, dQ/d ~(1+z) m - >10 19.3 eV: consistent with protons, 2 (dQ/d ) =0.5(+-0.2) x 10 44 erg/Mpc 3 yr + GZK UHE: Flux & Generation Spectrum ct eff [Mpc] GZK (CMB) suppression log( 2 dQ/d ) [erg/Mpc 2 yr]
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Intermediate E (10 6 GeV=1 PeV < E < 10 1.5 EeV)
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HE : UHECR bound p + N + 0 2 ; + e + + e + + Identify UHECR sources Study BH accretion/acceleration physics For all known sources, p <=1: If X-G p ’ s: Identify primaries, determine f(z) [EW & Bahcall 99; Bahcall & EW 01] [Berezinsky & Zatsepin 69]
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Bound implications: experiments 2 flavors, Fermi
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IceCube (preliminary) detection 28 events, compared to 12 expected, above 50TeV; ~4 (cutoff at 2PeV?) 1/E 2 spectrum, 4x10 -8 GeV/cm 2 s sr Consistent with e : : =1:1:1 Consistent with isotropy [N. Whitehorn, IC collaboration, IPA 2013] New era in astronomy
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IceCube (preliminary) detection 2 flavors,
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IceCube’s detection: Some implications Unlikely Galactic: E 2 ~10 -7 (E 0.1TeV ) -0.7 GeV/cm 2 s sr [Fermi] ~10 -9 (E 0.1PeV ) -0.7 GeV/cm 2 s sr XG distribution of sources, 2 (dQ/d ) >=0.5x 10 44 erg/Mpc 3 yr @ 10 6 GeV< E <10 9 GeV p, 2 (dQ/d ) PeV-EeV ~ 2 (dQ/d ) >10EeV, p(pp) >~1 Or: 2 (dQ/d ) PeV-EeV >> 2 (dQ/d ) >10EeV, p(pp) <<1 & Coincidence Isotropic, 1:1:1 flavor ratio, E 2 ~4x10 -8 GeV/cm 2 s sr~E 2 WB @ 50TeV<E<2PeV
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Low E (1GeV < E < 1TeV)
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Estimating the G-CR production rate CR production in the Galactic disk: Assuming CR production ~ SFR ~ SN rate, and using we have
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Galactic CR propagation models? For all secondaries: For positrons: At ~20GeV: f rad ~0.3~f 10 Be Predictions for e + & p consistent with PAMELA & AMS observations. Positron anomalies? -Due to assumptions adopted RE CR propagation. -Reflect the absence of a basic principles model. [Katz, Blum, Morag & EW 10; Blum Katz & EW 13] -
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Primary e+ sources DM annihilation [Hooper et al. 09] Pulsars [Kashiyama et al. 11]
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The cosmic ray generation spectrum XG CRs XG ’s Galactic CRs (+ CRs~SFR)
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Universal generation spectrum: Implications Natural: All CRs produced in galaxies, Rate ~ SFR [Loeb & EW 02; Parizot 05; Aublin et al. 05] 2 (dQ/d ) =0.5(+-0.2) x 10 44 erg/Mpc 3 yr If so, Galactic CR density 10 7 GeV Transient sources, currently “dim state” Implications/ Consistency checks: - E transient > E Galaxy (>10 7 GeV CRs)~10 50.5+-1.5 erg, consistent with strong explosions (SNe, GRBs) - Starburst emission
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The 10 20 eV challenge R B v v 2R t RF =R/ c) l =R/ 22 22 [Lovelace 76; EW 95, 04; Norman et al. 95]
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GRB: 10 19 L Sun, M BH ~1M sun, M~1M sun /s, ~10 2.5 AGN: 10 14 L Sun, M BH ~10 9 M sun, M~1M sun /yr, ~10 1 MQ: 10 5 L Sun, M BH ~1M sun, M~10 -8 M sun /yr, ~10 0.5 Source physics challenges Energy extraction Jet acceleration Jet content (kinetic/Poynting) Particle acceleration Radiation mechanisms [Reviews: Lemoine 13; Kirk 08, 13] [Reviws: GRBs Kouveliotou 94; Piran 05 AGN Begelman, Blandford & Rees 84 MQ HE: Aharonian et al 05; Khangulyan et al 07]
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UHE: Bright transients Electromagnetic acceleration in astrophysical sources requires L>L B >10 46 ( 2 / ) ( /Z 10 20 eV) 2 erg/s No steady sources at d<d GZK Transient Sources If electrons are accelerated with protons, transients should also be bright in X-ray/ The rate of such flares is much too low to account for the CR flux unless L> >10 50 erg/s >10 50 erg/s flares or Inefficient e-acceleration (“dark flares”) [EW & Loeb 09] [Lovelace 76; EW 95, 04; Norman et al. 95]
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High energy ’s from Star Bursts Starburst galaxies –{Star formation rate, density, B} ~ 10 3 x Milky way Most stars formed in z>1.5 star bursts –CR e’s lose all energy to synchrotron radiation, CR p’s likely lose all energy to production - If p’s lose all energy & radio bgnd dominated by starbursts: [Quataert et al. 06] Synchrotron radio (~1GeV) calibration [Loeb & EW 06]
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Mark Westmoquette (University College London), Jay Gallagher (University of Wisconsin-Madison), Linda Smith (University College London), WIYN//NSF, NASA/ESA Robert Gendler M82 M81
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[Loeb & EW 06] Starburst galaxies: emission Radio & bgnd’s consistent with 2 (dQ/d )~10 44 erg/Mpc 3 yr in galaxies, ~SFR, p(pp) >~1
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Are SNRs the low E CR sources? UHE, Intermediate E: Not yet identified Low E- SuperNova Remnants? [Baade & Swicky 34] So far, no clear evidence [ Gallant’s talk]. Electromagnetic observations- ambiguous (e.g. TeV e - I.C. [Katz & EW 08; Butt et al. 08] ). [e.g. Butt 09; Helder et al., SSR 12]
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Summary The identity of the CR source(s) is still debated. Many open Q’s RE candidate source(s) physics [accreting BHs]. 2 (dQ/d ) ~ 10 44 erg/Mpc 3 yr at all energies. Suggests: CRs of all E produced in galaxies @ a rate ~ SFR, by transients releasing ~10 50.5+-1.5 erg. IceCube detects XG n’s, ~ WB at 50TeV—1PeV - A new era in astronomy. - Consistent with the predictions of the ‘single source’ hypothesis, for p(pp) >~1 in StarBursts.
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A new era in HE ’ s IceCube ’ s sensitivity meets the minimum requirements for detection of XG sources. Preliminary detection of 50TeV-1PeV ’s. Bright transients are the prime targets. Coordinated wide field EM transient monitoring crucial: - Enhance detection sensitivity, - Identify sources, Enable physics output. XG detection rate limited (<~10/yr). Detection of a handful of ’ s from EM identified sources may resolve outstanding puzzles: - Identify UHECR (& G-CR) sources, - Resolve open “ cosmic-accelerator ” physics Q ’ s (related to BH-jet systems, particle acc., rad. mechanisms), - Constrain physics, LI, WEP.
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Back up slides
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Transient sources: GRB ’ s If: Baryonic jet Background free: [EW & Bahcall 97, 99; Rachen & Meszaros 98; Guetta et al. 01; Murase & Nagataki 06]
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IceCube’s limits [Hummer, Baerwald, and Winter 12; see also Li 12; He et al 12] IC40+59: No ’ s for ~200 GRBs (~2 expected). IC is achieving relevant sensitivity ! IC analyses overestimate GRB flux predictions, and ignore astrophysical uncertainties:
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G-XG Transition at ~10 18 eV? @ 10 18 eV: Fine tuning [Katz & EW 09] Inconsistent spectrumG cutoff @ 10 19 eV
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UHECR sources: Suspects Constraints: - L>10 12 ( 2 / ) L sun, > 10 2.5 (L 52 ) 1/10 ( t/10ms) -1/5 - 2 (dQ/d ) ~10 43.7 erg/Mpc 3 yr - d(10 20 eV)<d GZK ~100Mpc !! No L>10 12 L sun at d<d GZK Transient Sources Gamma-ray Bursts (GRBs) L ~ 10 19 L Sun >10 12 ( 2 / ) L sun = 10 17 ( / 10 2.5 ) 2 L sun ~ 10 2.5 (L 52 ) 1/10 ( t/10ms) -1/5 2 (dQ/d ) ~ 10 53 erg*10 -9.5 /Mpc 3 yr = 10 43.5 erg/Mpc 3 yr Transient: T ~10s << T p ~10 5 yr Active Galactic Nuclei (AGN, Steady): ~ 10 1 L>10 14 L Sun = few brightest !! Non at d<d GZK Invoke: * “ Hidden ” (proton only) AGN * L~ 10 14 L Sun, t~1month flares If e - accelerated: X/ observations rare L>10 17 L sun [Blandford 76; Lovelace 76] [EW 95, Vietri 95, Milgrom & Usov 95] [EW 95] [Boldt & Loewenstein 00] [Farrar & Gruzinov 08] [EW & Loeb 09]
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Bound implications: I. AGN models BBR05 “Hidden” ( only) sources Violating UHECR bound
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Single flavor Multi flavor [Anchordoqui & Montaruli 09]
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(Correct) detailed CR propagation models must agree with simple, analytic results derived from sec Example: Diffusion models with {D~K 0 , box height L} reproduce data for parameter combinations shown in fig. [Maurin et al. 01] Trivial explanation: [Katz, Blum & EW 09] Require sec ( =35GeV) to agree with the value inferred from B/C sec =[3.2,3.45,3.9] g/cm 2 [green, blue, red]
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